Generally, a violin, a cello, a guitar and the like are kinds of string instruments which produce sound by vibrating or plucking strings, and the string instruments are applicable to more various music genres when compared with other instruments.
For instance, the guitar is classified into acoustic guitar, base guitar, classic guitar, electric guitar and so on.
The guitar is made through a large number of production processes, and recently, mechanical machining processes have been increasingly applied to the manufacturing process of the guitar.
In the conventional guitar, however, the body of the guitar may be deformed due to the tension of the strings and the air flow in the sound resonance while is being played, and further, a top plate and a bottom plate of the body of the guitar may be deformed due to the surrounding environment (for example, humidity), which undesirably results in the changes in the original sound produced from the guitar.